Adsorption apparatus, semiconductor device manufacturing facility comprising the same, and method of recycling perfulorocompounds

Abstract

PFC is recycled from a gas mixture using adsorption technology and techniques. Two adsorption units each include an adsorbent having a selectivity by which the PFC is selectively adsorbed with respect to the other gas(es) that make up the mixture. The gas mixture is selectively supplied to one of the first and second adsorption units and a condition is created in the first adsorption unit so that the PFC is adsorbed in the first adsorption unit. Once the adsorbent is saturated in the first adsorption unit, a condition is created in the first adsorption unit that causes the PFC to be desorbed. At this time, the gas mixture is selectively supplied to the second adsorption unit, and a condition is created in the second adsorption unit so that the PFC is adsorbed. Once the adsorbent is saturated in the second adsorption unit, a condition is created in the second adsorption unit that causes the PFC to be desorbed. High-purity PFC gas can be obtained from the exhaust gas even if the gas mixture is exhaust gas of a semiconductor device manufacturing process having a low concentration of PFC.

1 . A method of recycling gas comprising a perfluorocompound (PFC), comprising: 
 a) supplying an exhaust gas mixture including a gas comprising a PFC to the first of first and second adsorption units each comprising an adsorbent, wherein the adsorbent has a selectivity by which the adsorbent selectively adsorbs the gas comprising a PFC with respect the mixture adsorbs under certain conditions, and wherein the adsorbent desorbs the gas comprising a PFC under certain other conditions;    b) creating a condition in the first adsorption unit under which the gas comprising a PFC will be adsorbed by the adsorbent of the first adsorption unit, until the adsorbent of the first adsorption unit is saturated with the PFC;    c) subsequently creating a condition in the first adsorption unit under which the the gas comprising a PFC is desorbed from the saturated adsorbent;    d) after the adsorbent of the first adsorption unit is saturated, selectively supplying the exhaust gas to the second of the first and second adsorption units;    e) creating a condition in the second adsorption unit under which the gas comprising a PFC will be adsorbed by the adsorbent of the first adsorption unit, until the adsorbent of the second adsorption unit is saturated with the PFC;    f) subsequently creating a condition in the second adsorption unit under which the gas comprising a PFC is desorbed from the saturated adsorbent of the second adsorption unit; and    g) recollecting the gas comprising a PFC desorbed by the adsorbents of the first and second adsorption units.    
   
   
       2 . The method of  claim 1 , wherein b)-e) are repeated after f).  
   
   
       3 . The method of  claim 2 , wherein c) and e) are simultaneously performed.  
   
   
       4 . The method of  claim 2 , wherein f) and b) are simultaneously performed.  
   
   
       5 . The method of  claim 2 , wherein b) comprises creating room temperature and atmospheric pressure in the first adsorption unit, and c) comprises creating a temperature higher than that of room temperature and a pressure lower than that of atmospheric pressure in the first adsorption unit.  
   
   
       6 . The method of  claim 2 , wherein b) comprises creating a temperature below room temperature and pressure greater than atmospheric pressure in the first adsorption unit, and c) comprises creating a temperature higher than that of room temperature and a pressure lower than that of atmospheric pressure in the first adsorption unit.  
   
   
       7 . The method of  claim 2 , wherein e) comprises creating room temperature and atmospheric pressure in the second adsorption unit, and f) comprises creating a temperature higher than that of room temperature and a pressure lower than that of atmospheric pressure in the second adsorption unit.  
   
   
       8 . The method of  claim 2 , wherein e) comprises creating a temperature below room temperature and pressure greater than atmospheric pressure in the second adsorption unit, and f) comprises creating a temperature higher than that of room temperature and a pressure lower than that of atmospheric pressure in the second adsorption unit.  
   
   
       9 . The method of  claim 2 , further comprising pressurizing the first adsorption unit before a).  
   
   
       10 . The method of  claim 9 , wherein the pressurizing of the first adsorption unit includes supplying gas of the mixture from the second adsorption unit, and which gas is not adsorbed by the adsorbent of the second adsorption unit, to the first adsorption unit.  
   
   
       11 . The method of  claim 2 , further comprising pressurizing the second adsorption unit before d).  
   
   
       12 . The method of  claim 11 , wherein the pressurizing of the second adsorption unit includes supplying gas of the mixture from the first adsorption unit, and which gas is not adsorbed in the first adsorption unit, to the second adsorption unit.  
   
   
       13 . A method of recycling a gas comprising a perfluorocompound (PFC), comprising: 
 a) pressurizing a first adsorption unit comprising an adsorbent, and supplying a gas mixture including a gas comprising a PFC to the first adsorption unit, wherein the adsorbent has a selectivity by which the adsorbent selectively adsorbs the gas comprising a PFC with respect the mixture;    b) subsequently creating a condition in the, first adsorption unit under which the PFC gas is desorbed from adsorbent of the first adsorption unit and simultaneously pressurizing a second adsorption unit comprising an adsorbent, and supplying the gas mixture to the second adsorption unit, wherein the adsorbent of the second adsorbent unit has a selectivity by which the adsorbent selectively adsorbs the gas comprising a PFC with respect the mixture; and    c) subsequently creating a condition in the second adsorption unit under which the gas comprising a PFC is desorbed from the adsorbent of the second adsorption unit and simultaneously pressurizing the first adsorption unit, and supplying the first adsorption unit with the gas mixture.    
   
   
       14 . The method of  claim 13 , wherein the pressurizing of the first adsorption unit in a) includes supplying nitrogen into the first adsorption unit.  
   
   
       15 . The method of  claim 13 , wherein the pressurizing of the second adsorption unit in b) includes supplying gas of the mixture from the first adsorption unit, and which gas is not adsorbed by the adsorbent of the first adsorption unit, to the second adsorption unit.  
   
   
       16 . The method of  claim 13 , wherein the pressurizing the first adsorption unit of c) includes supplying gas of the mixture from the second adsorption unit, and which gas is not adsorbed by the adsorbent of the second adsorption unit, to the first adsorption unit.  
   
   
       17 . An adsorption apparatus for recycling a gas comprising a perfluorocompound (PFC), comprising: 
 first and second adsorption units each comprising a housing, an inlet and an outlet, and an adsorbent disposed in the housing between the inlet and outlet, the adsorbent having the ability to absorb a gas comprising a PFC;    a first pipe to which the inlets of the first and second adsorption units are commonly connected;    valves disposed in-line between the first pipe and the inlets of the first and second adsorption units, respectively, whereby the valves are positionable to allow gas flowing through the first pipe to be selectively supplied to the first and second adsorption units;    second and third pipes respectively connected to the outlets of the first and second adsorption units;    valves disposed in-line with the second and third pipes, respectively;    a fourth pipe interconnecting the first and second adsorption units; and    and a valve disposed in-line with the fourth pipe, whereby the valves are movable to positions at which gas that is not adsorbed by the adsorbent of the first adsorption unit flows through the fourth pipe into the second adsorption unit, and to positions at which gas that is not adsorbed by the adsorbent of the second adsorption unit flows through the fourth pipe into the first adsorption unit.    
   
   
       18 . The adsorption apparatus of  claim 17 , further comprising a storage tank connected to the second and third pipes.  
   
   
       19 . The adsorption apparatus of  claim 17 , wherein the adsorbent is selected from the group consisting of silica gel, activated alumina, zeolite, and activated carbon.  
   
   
       20 . The adsorption apparatus of  claim 19 , wherein the adsorbent is activated carbon.  
   
   
       21 . A semiconductor device manufacturing facility comprising: 
 semiconductor device manufacturing equipment including a reaction chamber in which substrates are processed using a gas comprising a perfluorocompound (PFC), and an exhaust system including an exhaust line through which gas is discharged from the reaction chamber;    first and second adsorption units each comprising a housing, an inlet and an outlet, and an adsorbent disposed in the housing between the inlet and outlet, the adsorbent having the ability to absorb a gas comprising a PFC;    a first pipe connected to the exhaust line of the semiconductor device manufacturing equipment and to the inlets of the first and second adsorption units;    valves disposed in-line between the first pipe and the inlets of the first and second adsorption units, respectively, whereby the valves are positionable to allow exhaust gas flowing from the semiconductor manufacturing equipment through the first pipe to be selectively supplied to the first and second adsorption units;    second and third pipes respectively connected to the outlets of the first and second adsorption units; and    valves disposed in-line with the second and third pipes, respectively.    
   
   
       22 . The semiconductor device manufacturing facility, further comprising: 
 a fourth pipe interconnecting the first and second adsorption units; and    and a valve disposed in-line with the fourth pipe, whereby the valves are movable to positions at which gas that is not adsorbed by the adsorbent of the first adsorption unit flows through the fourth pipe into the second adsorption unit, and to positions at which gas that is not adsorbed by the adsorbent of the second adsorption unit flows through the fourth pipe into the first adsorption unit.